A sapiosexual is someone that is sexually and mentally turned on by smart people. Sapiosexuals are aroused by intelligence.
One who finds the content's of someone else's mind to be their most attractive attribute, above and before their physical characteristics. From the Latin root "sapien", meaning wise. The term is now becoming mainstream with dating apps such as OkCupid and Sapio giving users the ability to define their sexual orientations as "Sapiosexual."
For many, defining oneself as Sapiosexual is also a statement against the current status quo of hookup culture and superficiality, where looks are prized above all else.